The present invention is related generally to electrical test equipment and more specifically to electrical test equipment used for testing electric motors.
The need to make test measurements on electric motors in order to insure the absence of winding anomalies and defective connections to the terminals is well known. A typical case where these tests are needed is represented by the wound armatures of commutator type motors.
One of the difficulties encountered during these tests is the difference in values between the coil resistance itself and the resistance of the connections between the coils and the commutator bars. Therefore, the straightforward measurement of the resistance between two commutator bars to which the tangs of one coil are connected is not satisfactory. In fact, a defective connection between the coil and the commutator bar does not necessarily lead to a measured resistance that is so high as to be distinctly outside the tolerance limits for such a measurement. Thus, when making measurements between two commutator bars an eventual fault due to a faulty winding or a bad connection between the coil and the commutator bar may not be recognized.